Image diagnostic technologies (optical imaging technologies) are technologies widely used for mechanical devices and medical treatment fields. For example, in a manufacturing field of precision instruments, schemes such as X-ray computed tomography (CT) capable of capturing a tomographic image or a three-dimensional (3D) tomographic image, nuclear magnetic resonance, an optical coherence tomography (OCT) image using coherency of light, in addition to general camera observation and ultrasonic diagnostic equipment have been researched and used as means for an examination of an inner part of a deep hole and image diagnosis. In particular, referring to capturing of the tomographic image or the 3D tomographic image, the development of the OCT image diagnosis technology that obtains the most microscopic captured image has been recently drawing attention among the schemes.
The OCT image frequently uses far-red light having a wavelength of about 1,300 nanometers (nm) or a laser beam having a wavelength of about 400 nm as a light source, and each of the far-red light and the laser beam has a shorter wavelength than that of an ultrasonic wave, and thus is excellent in spatial resolving power. When a tomographic scheme is included in an endoscope, it is possible to achieve excellent spatial resolving power of about 10 micrometers (μm) or less [less than or equal to a ten of that of the ultrasonic diagnostic equipment].
In addition, the near infrared ray as a light source has non-invasiveness with respect to a living body. In particular, the near infrared ray is expected to be used to detect, diagnose, and treat a diseased part in a gastric region, a small intestine region, and a blood vessel part of an arterial flow or the like of a human body in the medical treatment field. For example, a representative configuration of an OCT endoscope to which this OCT image technology for mechanical devices and medical use is applied is as indicated in Patent Document 1.
Incidentally, in the OCT endoscope indicated in Patent Document 1, as illustrated in FIG. 8 of the document, a torque of a motor is delivered to a rotating shaft through a belt, and delivered to a lens unit through a flexible shaft which passes through an optical sheath having a shape of a tube and includes an optical fiber or the like. For this reason, in some cases, abrasion powder is generated due to friction between an inner peripheral surface of the optical sheath and the flexible shaft. In addition, rotation speed unevenness, rotation transmission delay, variation of torque loss, and the like have occurred due to friction, deflection, and torsion of the flexible shaft, elastic deformation of the belt, or the like. Thus, an obtained OCT analyzed image has been in disorder, and requested spatial resolving power has not been acquired. Further, even though a two-dimensional (2D) tomographic image illustrated in FIG. 26 of the document can be obtained using the configuration, a 3D image cannot be obtained using the configuration.
In addition, an OCT endoscope illustrated in Patent Document 2 corresponds to a 3D image system in which a catheter having a shape of a long and thin tube is inserted into a circular guide catheter illustrated in FIG. 1 of the document, an optically-connected optical fiber or core which is rotatable and slidable is included in the catheter, and the optical fiber is rotated and moved in a longitudinal direction as illustrated in FIG. 3 of the document to irradiate a body tissue, thereby observing an OCT analyzed image. However, this configuration has a problem in that abrasion powder is generated due to friction between the inner peripheral surface of the catheter and an outer peripheral surface of a drive shaft. In addition, rotation speed unevenness, rotation transmission delay, change of torque loss, and the like have occurred due to friction, deflection, and torsion of the drive shaft, and thus an obtained analyzed image has been in disorder, and requested spatial resolving power has not been acquired.
In addition, in the invention disclosed in Patent Document 3, a reflecting mirror is directly connected to a tip of a rotating shaft of a motor illustrated in FIG. 2 of the document. However, in this configuration, even though a 2D tomographic image can be obtained using the reflecting mirror which rotates, a 3D image cannot be obtained.